@@ -2073,7 +2073,7 @@ static ssize_t tun_put_user_xdp(struct tun_struct *tun,
if (unlikely(copy_to_iter(&gso, sizeof(gso), iter) !=
sizeof(gso)))
return -EFAULT;
- iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
+ iov_iter_zero(vnet_hdr_sz - sizeof(gso), iter);
}
ret = copy_to_iter(xdp_frame->data, size, iter) + vnet_hdr_sz;
@@ -2146,7 +2146,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
return -EFAULT;
- iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
+ iov_iter_zero(vnet_hdr_sz - sizeof(gso), iter);
}
if (vlan_hlen) {
tun used to simply advance iov_iter when it needs to pad virtio header. This leaves the garbage in the buffer as is and prevents telling if the header is padded or contains some real data. In theory, a user of tun can fill the buffer with zero before calling read() to avoid such a problem, but leaving the garbage in the buffer is awkward anyway so fill the buffer in tun. Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> --- drivers/net/tun.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)